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J. PFEIF]E'E'.R.-

GRINDING MILL.

No. 577,319. Patented Feb. 16, 1897.

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J. PFEIPFER.

GRINDING MILL.

No. 577,319.. Patgn'ted Feb. 16, 1897.

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. ATfOHNEYS I UNTTED STATES PATENT rrrcn.

JACOB PFEIFFER, OF KAISERSLAUTERN, GERMANY.

GRINDING-MILL.

SPECIFICATION forming part of Letters Patent No. 577,319, dated February 16, 1897.

Application filed September 4, 1895. Serial No. 561,446. (No model.)

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Be it known that I, JACOB PFEIFFER, a subject of the King of Bavaria, residing at Kaiserslautern, in the Kingdom of Bavaria, Germany, have invented new and useful Improvements in Grinding-Mills, of which the following is a specification.

My invention relates to an improved construction of ball grinding-mills with windseparator,wherein the use of sieves is avoided.

The new ball grinding-mill is shown in the accompanying drawings, in which- Figure 1 is a vertical section, and Fig. 2 a horizontal section, of the mill on the line 00 0c in Fig. 1.

In a hollowed grinding-ring R balls k are driven round by arms I), actuated by a shaft a, and they effect the grinding of the material introduced through a central hopper g. The grinding-ring It carries a casing 171, enlarged at the top and to which is secured the cylindrical casing 01. To the latter is fixed a second casing 0 in such a manner that the casing 02 is concentric with respect to the easing 0,which extends downward nearly to the casing m. Above the casings n and 0 a fan is arranged,which is connected with the central hopper g. The hopper g is secured to the arms I), so that it is also revolved by the shaft a. A casing 19 incloses the whole arrangement in such a manner that it covers the fan 0 at the top up to the central hopper,

' while laterally there is left between the easings p and at an annular space,which is closed at the bottom and provided with the tubular discharge-pipe h.

The above-described mill works in such a manner that the reduced pulverized material rises upward in the casing 0 and is drawn out by the fan and thrown into the annular space .between the casings p and n, whence it is discharged through the discharge-pipe h.

In the above-described construction I have found a disadvantage, namely, that not only reduced pulverized material but also grits are led off by the fan 0. The reason thereof is that the air layer contained in the interior of the casing o is put in revolution corresponding to the revolving parts, z'. e., to the hopper g and to the arms b, so that the incompletely-reduced parts of the material, that is to say, grits, are raised by the produced air whirl and pass through the fan 0 to the discharge-pipe. To remedy this drawback, I have made the following arrangement,which is the essential new feature and attains the object of this invention.

Within the casing 0 there are inserted radially-arranged vanes d, firmly connected with the casing 0, as shown in Figs. 1 and 2. The inner lower border of these vanes is connected with a ring 61, embracing the flaring lower end of the central hopper or feed-tube g. By means of this ring and the vanes the grits whirled up are thrown against the revolving central hopper g and thus raised upward. Furthermore, by means of the vanes 01 a revolving air column is formed within the mill, which carries away upward the coarser parts, 2'. a, the grits, as above explained. When the mill provided with these improvements is working, the grits thrown against the vanes 01 fall down again into the grinding-space, so that only reduced pulverized material is drawn out.

The flat rings on the upper end of the casing 0 and the flange 0 on the fans 0 serve to prevent the ground grain from passing between the fans and the casings and going into the space between the casings 0 and n. The casings 0 and n are provided for the purpose of rendering thestructure rigid and durable. They do not affect the principle of the apparatus.

I claim 1. In a grinding-mill, the combination of a shaft, grinding mechanism actuated thereby, a casing inclosing the grinding mechanism, a feed-hopper extending centrally through the casing, an exhaust-fan, a vane rigid with the casing and interposed between the fan and grinding mechanism, and a ring held to the vanes and below the same and embracing the feed-hopper, substantially as described.

2. In a grinding-mill, the combination of a casing, a shaft, grinding mechanism carried by the shaft and within the casing, a hopper axially coincident to and revolving with the shaft, a casing n concentric with and within the first casing and arranged to leave an annular space between the two, a casing 0 withinthe casing 01. and secured thereto, a fan carried by the hopper and above the casings 'n, and o, vanes projecting inwardly from the casing o, and a ring held by and below the vanes and emb 'acing the hopper, substantially as described.

3. In a grinding-mill, the combination with a base, of a drive-shaft, a series of radial arms carried by the drive-shaft, a grinding-ring held on the base and embracing the arms, grin ding-balls confined by the ring and driven by the arms, a centrally-disposed hopper leading downward to the arms and grinding-ring and carried by the arms, an exterior casing rigid with the base, a second casing within the first and also rigid with the base, the two cas ings forming between them an outlet-passage for the pulverized material, a fan carried by the hopper and moving therewith, the fan be ing located at the upper edge of the inner casing, and a series of radial vanes rigidly carried by the inner casing, the vanes projecting into the space surrounding said hopper to prevent the formation of a swirling current of air, substantially as described.

4. In a grinding-mill, a base having a grinding-ring, a drivin shaft, arms mounted on the shaft and inclosed by the ring, balls driven by the arms, a hopper carried by the arms and rising from the same, the hopper leading to the space inelosed by the ring, a fan carried and driven by the hopper, a casing rigid with the base, the casing being located beneath the fan and the parts being arranged so that a current of pulverized material may pass upward through the casing, and a series of vanes rigid on the interior of the casing, the vanes projecting radially and inward to prevent the formation of a swirling current of air, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JACOB PFEIFFER.

Witnesses:

P. BENDER, E. SOHIMPER. 

